I would estimate that on average, I get two weeks of very heavy use on one pair of lithium ion batteries. This is reading mixed text and Audible book (MP3) content, for an average of probably five hours a day. If I'm only reading text content, double that. With anything other than plain alkalines, the one thing you *must* be careful of is the battery power indicator (keys D+F), since it will not give accurate readings for the percentage of battery life remaining for anything but alkalines. For this reason, I make sure never to be too far from a pair of replacement batteries. _____ From: bookport-bounce@xxxxxxxxxxxxx [mailto:bookport-bounce@xxxxxxxxxxxxx] On Behalf Of M BROWN Sent: Thursday, February 21, 2008 11:05 AM To: bookport@xxxxxxxxxxxxx Subject: [bookport] Re: some info Firstly, thank you for your response. How long do you get, on average, from a set of lithium ion. Many thanks M Brown